datafusion/execution/src/cache/mod.rs

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//   http://www.apache.org/licenses/LICENSE-2.0
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pub mod cache_manager;
pub mod cache_unit;
pub mod lru_queue;

/// The cache accessor, users usually working on this interface while manipulating caches.
/// This interface does not get `mut` references and thus has to handle its own
/// locking via internal mutability. It can be accessed via multiple concurrent queries
/// during planning and execution.
pub trait CacheAccessor<K, V>: Send + Sync {
    // Extra info but not part of the cache key or cache value.
    type Extra: Clone;

    /// Get value from cache.
    fn get(&self, k: &K) -> Option<V>;
    /// Get value from cache.
    fn get_with_extra(&self, k: &K, e: &Self::Extra) -> Option<V>;
    /// Put value into cache. Returns the old value associated with the key if there was one.
    fn put(&self, key: &K, value: V) -> Option<V>;
    /// Put value into cache. Returns the old value associated with the key if there was one.
    fn put_with_extra(&self, key: &K, value: V, e: &Self::Extra) -> Option<V>;
    /// Remove an entry from the cache, returning value if they existed in the map.
    fn remove(&mut self, k: &K) -> Option<V>;
    /// Check if the cache contains a specific key.
    fn contains_key(&self, k: &K) -> bool;
    /// Fetch the total number of cache entries.
    fn len(&self) -> usize;
    /// Check if the Cache collection is empty or not.
    fn is_empty(&self) -> bool {
        self.len() == 0
    }
    /// Remove all entries from the cache.
    fn clear(&self);
    /// Return the cache name.
    fn name(&self) -> String;
}